#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    vector<int> findDisappearedNumbers(vector<int>& nums) {
        int n = nums.size();
        vector<int> v(n + 1, 0);
        for (auto e : nums)
        {
            v[e]++;
        }
        vector<int> ans;
        for (int i = 1; i <= n; i++)
        {
            if (v[i] == 0)
                ans.push_back(i);
        }
        return ans;
    }
};